Apart from the varying health warnings and images the only difference between the packs, mandatory from Saturday, are the brand names, and these are all printed in identical small font. It is the world's most strict regime for the packaging of tobacco.

Plain packaging for cigarettes and tobacco has come into force in Australia. Photograph: AFP/Getty/Australian government

Australia's federal government says the aim is to deter young people from smoking by stripping the habit of glamour. It is relying on studies showing that if people have not started smoking by age 26 there is a 99% chance they will never take it up.

"Even from a very early age you can see that kids understand the message that the tobacco company is trying to sell through their branding," said the federal health minister, Tanya Plibersek, citing studies that showed, for example, children linking a crown in a logo with the idea of being a princess.

While Australia has one of the world's lowest smoking rates and the changes will have little impact on multinationals' profits, other countries are considering similar steps.

The tobacco industry lobbied hard against the laws. Tobacco firms said they would boost black market trade, leading to cheaper, more accessible cigarettes. "There will be serious unintended consequences from the legislation," said Scott McIntyre of British American Tobacco Australia. "Counterfeiters from China and Indonesia will bring lots more of these products down to sell on the streets of Australia." Others say the laws have boosted their business. Sandra Ha of Zico Import Pty Ltd, a small family business, said demand for cigarette cases, silicon covers to mask the unpalatable packages, had shot up from almost nothing two months ago since British American Tobacco, Britain's Imperial Tobacco, Philip Morris and Japan Tobacco lost a challenge to the laws in Australia's high court. Ha said Zico had sold up to 6,000 to wholesale outlets and was awaiting new stock. "This is good business for us."

The potential hitch, experts say, is the popularity of social media with the very demographic the plan is targeting. After a series of Australian laws banning TV advertising and sports sponsorship and requiring most sellers to hide cigarettes from view, tobacco marketing has moved online. Australia has banned web advertising by local companies and sites but cannot restrict overseas sites. "If you are a tobacco marketer and you've only got this small window left to promote your products, online is the compelling place for you to be in," said Becky Freeman, a public health researcher at Sydney University.

Freeman noted an increase in "average Joe" reviews of brands on social media sites such as YouTube, Twitter and Facebook. "We have to ask, is that just a private citizen who really loves Marlboro cigarettes and they've gone to the trouble of making a video, or is there a marketing company involved?"

British American Tobacco Australia said the industry was focused on dealing with the new rules rather than marketing.

The industry has gone as far as paying for Ukraine, Honduras and the Dominican Republic to challenge the new rules – the countries are claiming at the World Trade Organisation that trade is being unfairly restricted, despite none of the countries having significant trade with Australia. A WTO ruling is likely in mid-2013.

Plibersek said the government had held discussions with other countries considering similar laws on packaging.

Canada was the first country to make photograph warnings mandatory in 2001. They now extend to more than 40 countries including Brazil, Turkey and Ukraine. Tougher laws are being considered in Britain, New Zealand, South Africa and India.

Many smokers in Australia remain defiant. "The pictures don't affect me. I just ignore them. You just grab a smoke and put it away," said Victor El Hage as he purchased a pack with a photograph of a mouth tumour. "Honestly, there's only one reason I'd stop, and that's my little girl."

James Yu, who runs the King of the Pack tobacconist in central Sydney, said the uniform packaging made it harder to stack his shelves "It used to take me an hour to unload a delivery, now it takes me four hours," Yu said. "The government should have just banned them altogether and then we'd go OK, fine, we're done, we'll shut up shop," he said, throwing his hands up in the air.